A pump system is disclosed. The pump system includes a cavity (102) comprising one or more inlet check valves (120, 122) and one or more outlet check valves (124, 126). A piston (104) having an enlargement (106) at a substantially middle portion of the piston (104). The piston (104) is capable of moving within the cavity (102) for forming a first chamber (116) and a second chamber (118), wherein up movement of the piston (104) the volume in the first chamber (112) is increased and simultaneously the volume in the second chamber (118) is decreased and vice versa.

An infusion system includes a double action infusion pump. The pump includes a cylinder and a reciprocating piston received within the cylinder, the reciprocating piston separating a first pump chamber from a second pump chamber of the cylinder. A reciprocating motor is coupled with the reciprocating piston, and the first and second pump chambers alternate between filling and evacuating conditions with reciprocation of the reciprocating piston through operation of the reciprocating motor, and the speed of reciprocation is varied to provide a continuous output of fluid between the first and second pump chambers. A fluid source and a catheter are optionally coupled with the double action infusion pump. The catheter includes one or more infusion ports near a catheter distal portion, and the one or more infusion ports receive and expel the continuous output of fluid from the double action infusion pump.

An infusion system includes a double action infusion pump. The pump includes a cylinder and a reciprocating piston received within the cylinder, the reciprocating piston separating a first pump chamber from a second pump chamber of the cylinder. A reciprocating motor is coupled with the reciprocating piston, and the first and second pump chambers alternate between filling and evacuating conditions with reciprocation of the reciprocating piston through operation of the reciprocating motor, and the speed of reciprocation is varied to provide a continuous output of fluid between the first and second pump chambers. A fluid source and a catheter are optionally coupled with the double action infusion pump. The catheter includes one or more infusion ports near a catheter distal portion, and the one or more infusion ports receive and expel the continuous output of fluid from the double action infusion pump.

The present invention discloses ventilation apparatus, comprising a casing with a first vent and a second vent, a fixed spacer disposed within the casing, and a movable spacer in operative connection with a power mechanism. Also discloses herein are methods for ventilating a subject, by synchronously providing a positive pressure ventilation and a negative pressure ventilation using the ventilation apparatus described herein.

A vehicle-mounted electric oil-free air compressor, including a motor, a box body, a piston, and a flywheel shaft. The motor is fixed on the box body, a cylinder cover is at the top of the box body, a main shaft of the motor includes a coupling driving end, the flywheel shaft is driven by an elastic body to rotate. The piston includes a primary intake valve piece and a primary exhaust valve piece, the box body is provided with a secondary cavity, a secondary exhaust valve piece is provided at a vent hole on one side of the cavity, and the primary exhaust valve piece is also a secondary intake valve piece of the compressor, increasing the exhaust pressure. When the piston reciprocates, the stress is balanced and the vibration is small, and with the assistance of a high-efficiency flywheel, the operation of the air compressor is stable.

A vehicle-mounted electric oil-free air compressor, including a motor, a box body, a piston, and a flywheel shaft. The motor is fixed on the box body, a cylinder cover is at the top of the box body, a main shaft of the motor includes a coupling driving end, the flywheel shaft is driven by an elastic body to rotate. The piston includes a primary intake valve piece and a primary exhaust valve piece, the box body is provided with a secondary cavity, a secondary exhaust valve piece is provided at a vent hole on one side of the cavity, and the primary exhaust valve piece is also a secondary intake valve piece of the compressor, increasing the exhaust pressure. When the piston reciprocates, the stress is balanced and the vibration is small, and with the assistance of a high-efficiency flywheel, the operation of the air compressor is stable.

A reciprocating gas horizontal compressor with free lifting piston, which includes a piston with straight ends and inclined compression chambers, a crankcase in which are mounted a crankshaft, a connecting rod fixed to a cross head thru a bolt which alternately drives in a cross-head body a piston rod, and a cylinder body which contains a cylinder liner in which is moving rectilinear and alternatively an improved piston provided with straight ends and compression chambers inclined in areas (m) and (k), with the same angle and in the same plane as a zone (p) from a first cylinder head element and respectively in a zone (n) from a second cylinder head element, and some magnets fixed to the piston and some magnets fixed outside and to a lower part of the cylinder liner, through which the piston is free lifting on the stroke length with reduced friction.

A reciprocating gas horizontal compressor with free lifting piston, which includes a piston with straight ends and inclined compression chambers, a crankcase in which are mounted a crankshaft, a connecting rod fixed to a cross head thru a bolt which alternately drives in a cross-head body a piston rod, and a cylinder body which contains a cylinder liner in which is moving rectilinear and alternatively an improved piston provided with straight ends and compression chambers inclined in areas (m) and (k), with the same angle and in the same plane as a zone (p) from a first cylinder head element and respectively in a zone (n) from a second cylinder head element, and some magnets fixed to the piston and some magnets fixed outside and to a lower part of the cylinder liner, through which the piston is free lifting on the stroke length with reduced friction.

Embodiments provide for two rotating parallel discs to power horizontal pistons back and forth configured in a radial pattern, comprised of double acting fluid end that may be used in high pressure fluid handling equipment, wherein the fluid end has an arrangement that acts upon both a suction and a discharge operation.

Embodiments provide for two rotating parallel discs to power horizontal pistons back and forth configured in a radial pattern, comprised of double acting fluid end that may be used in high pressure fluid handling equipment, wherein the fluid end has an arrangement that acts upon both a suction and a discharge operation.